Your old TV still works even with an adaptor - but there's no such a method for the phone.
I want my phone to work until the hardware fails, not when apple decides they want to push people to buy a new one next quarter.
As of December 31, 2022, U.S. telcos* decommed the 3G tech phones of the mid-2000s used.
As long as your iPhone can still use the telco network, it still does the functions it shipped with just fine.
A phone's environment depends on a lot more than its hardware maker.
(FWIW, thanks to its different incentives than other handset makers, Apple continues to offer the longest average OS support of the hardware and OS giants. Google's Pixel 8 is the first to bump Google's 3 years to match Apple's 7, and Samsung's S24 also finally matches 7 years. So on current devices, they stepped up, but on devices before 2023, Apple's support is more than double theirs. Arguably, these two finally stepping up were in response to the "environment" of Apple's incentives and EU regs.)
* Verizon was the last. AT&T turned off its 3G network on February 22, 2022. T-Mobile dismantled Sprint's 3G CDMA network on March 31, 2022, and its own 3G UMTS network on July 1, 2022.
I consider that "everything around it" (The Ecosystem, as they say) to be part of the product I bought. When I bought my OldPhone N years ago, I could go to the app store and download versions X, Y, and Z of apps A, B, and C, and they worked. I expect today that if I factory reset that OldPhone back to fresh, I'd still be able to re-download those compatible versions of those apps, and that those apps continued to work as they did N years ago (barring some obvious, but still unfortunate cases like companies going out of business or turning down online services). That's my bar for "working."
If the world moves on, and people are sharing image formats that my phone was never able to read in the first place, or writing web pages my browser was never able to render correctly, then I have to accept that. But what I don't accept is the device manufacturer, or (usually the case) 3rd party apps telling me "your phone is too old, and we're no longer going to let you use it as you have for the last N years anymore!"
> What is so special about phones where we allow them to be considered obsolete so quickly?
The phone / computer works exactly as it did when you bought it. What changed is everything around it. That's not true of those other things. New video codex, new services, new sites, new apps. Let's pick ChatGPT. They have app. It's about 2 years old? It strictly costs them more money to cover older hardware than just not supporting it. And, going forward, each year they want to support the newest phones/OS but keeping support for both strictly increases costs. I work on a project that run on nearly every device (Windows/Mac/Linux/iOS/Android) and we are always evaluating which devices we can stop supporting and what new devices we need to add to our testing infra going forward.
Your 18yr old TV is great. It works exactly as it did when you bought it. But for example, let say your TV was 25 years old. It wouldn't have HDMI and there for, without expensive adapters, would not work with an XBox, PS5, Switch (afaik).
The point is, your TV does exactly what it did when you bought it. No changes. For a smartphone to keep working requires constant changes. As a simple example, HEIF images didn't exist before. JPEG's with gain maps didn't exist. Zoom didn't exist. Etc... Your phone needs constant updating. Your TV, A/V receiver, speakers, thermostat do not. It costs money to keep the phone up to date. It costs nothing to keep the TV, A/V receiver, speakers and termostat up to date because there is nothing to update